INTRODUCTION: Breast cancer is the most common cancer in women. Lymph node involvement is the most important prognostic factor. Correlation between microvessel count (MVC) and lymph node involvement has been shown by several studies. This study investigates the correlation between tumor angiogenesis and lymph node involvement, tumor histological grade and the patients age. This study was conducted to evaluate the relationship between tumor angiogenesis and lymph node involvement in breast cancer.METHODS: In this analytical-descriptive study, 170 formalin-fixed and paraffin-embedded breast cancer tissue specimens were stained for factor VIII-related antigen. Samples were classified according to the number of involved lymph nodes, histological grade and age. Finally the correlation between these parameters and MVC was examined. T-student and ANOVA tests were used for statistical analysis.RESULTS: The difference observed between MVC, and the number of involved lymph nodes and histological grade was significant (P<0.0001, P< 0.0005), whereas there was no significant difference between MVC and age.DISCUSSION: A significant correlation was seen between MVC and the number of involved lymph nodes. As a result, tumors with high MVC are associated with the highest possibility of lymph node involvement and patients gain from anti-angiogenesis therapy.